How can I make my cold worse and last longer(please answer this is important)?

I have a cold but its not very strong and I think its starting to go away. How I can make myself sicker? Can you tell me how to make my nose run more or get really congested and sneeze alot? I don't have a cough can you tell me how to get a bad one? Please I really need to do this. I need to stay home and my parents won't let me inless I'm really, really sick. I can't fake at all so please don't suggest that. So how can I make myself get a really bad cold?